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Can I combine my oil-fired forced air furnace & oil-fired domestic hot water heater? And then tie in solar heated water? Answered

Currently, we have an oil-fired forced air furnace and an oil-fired domestic hot water heater.  I would like to combine the domestic hot water heater and the furnace somehow so we can heat them both by solar heated water from a panel on the roof, and use oil as a back up fuel.


In the UK and Europe we can buy "thermal stores" or "heat banks" which are very large (200-400 litre) tanks of water  with heat exchangers inside. The water is heated by any source you happen to have, and is circulated into where you want it via the heat exchangers, so you can use solar or oil or gas  and there is even a position for an electric heater.

I don't know if you can get them in the USA. The tanks don't use pressurised water and so are completely safe.


One option would be to pre-heat the cold water supply to the hot water heater with the solar panel. That is to run water around the panel into a tank in the roof space, have the hot water heater take it's supply from there, and run a cold water supply to the tank with a standard ball-cock.
If you're collecting enough sun to heat the building you probably don't need the air heater, if you're not the solar input isn't going to give you much hot air.